AAE 334 exam 2 || 100% Errorless Answers.
what causes induced drag correct answers There is always trailing vorticity in the wake for a
finite wing with non zero lift. This vorticity causes downwash. Downwash effects the
freestream direction experienced by the wing, and rotates the lift vector slightly backwards.
The component of lift that resists forward motion is induced drag
Why does a starting vortex appear correct answers The circulation around a material curve is
constant in inviscid flow. Since the circulation is initially zero, the circulation around the
airfoil must be balanced with a strating vortex of opposite sign.
Induced drag can be explained by
a-rotation of lift vector through induced angle of sttack
b-viscous friction
c- loss of flow energy to the wingtip vorticies correct answers a&c
In a super sonic wind tunnel, which of the following is true correct answers To>Te
downwash correct answers velocity induced on the airfoil by the trailing vorticity in the
wake. it changes the angle of attack seen by the airfoil
A vortext cannot end in the fluid it must correct answers go to infinity
terminate on a boundary
close on itself
Horseshoe vortex model load distribution correct answers constant
More realistic load distribution correct answers its a curve
Weakness of Prandtly Lifting line correct answers flaps, youre treating syestem as flat sheet
induced drag alpha eff correct answers alphaeff=alpha-alphai
Elliptic lift distribution gives correct answers uniform downwash and uniform induced angle
of attack
Relationship between AR and CDI correct answers AR reduces CDI
Elliptic distribution loading is ideal bc correct answers it reduces the drag for that aspect ratio
shape
Steps to prandtl correct answers substitute series
2. combine terms.
3. enforce at a number of points bc n unknowns and n equations
Elliptic circulation distribution ____ for a fixed wingspace correct answers minimizes iduced
drag
Rectangle wing oswald efficiency factor correct answers not a huge change, but even a few
percent is significant
what causes induced drag correct answers There is always trailing vorticity in the wake for a
finite wing with non zero lift. This vorticity causes downwash. Downwash effects the
freestream direction experienced by the wing, and rotates the lift vector slightly backwards.
The component of lift that resists forward motion is induced drag
Why does a starting vortex appear correct answers The circulation around a material curve is
constant in inviscid flow. Since the circulation is initially zero, the circulation around the
airfoil must be balanced with a strating vortex of opposite sign.
Induced drag can be explained by
a-rotation of lift vector through induced angle of sttack
b-viscous friction
c- loss of flow energy to the wingtip vorticies correct answers a&c
In a super sonic wind tunnel, which of the following is true correct answers To>Te
downwash correct answers velocity induced on the airfoil by the trailing vorticity in the
wake. it changes the angle of attack seen by the airfoil
A vortext cannot end in the fluid it must correct answers go to infinity
terminate on a boundary
close on itself
Horseshoe vortex model load distribution correct answers constant
More realistic load distribution correct answers its a curve
Weakness of Prandtly Lifting line correct answers flaps, youre treating syestem as flat sheet
induced drag alpha eff correct answers alphaeff=alpha-alphai
Elliptic lift distribution gives correct answers uniform downwash and uniform induced angle
of attack
Relationship between AR and CDI correct answers AR reduces CDI
Elliptic distribution loading is ideal bc correct answers it reduces the drag for that aspect ratio
shape
Steps to prandtl correct answers substitute series
2. combine terms.
3. enforce at a number of points bc n unknowns and n equations
Elliptic circulation distribution ____ for a fixed wingspace correct answers minimizes iduced
drag
Rectangle wing oswald efficiency factor correct answers not a huge change, but even a few
percent is significant
